Perform profile file analysis in dex2oat

Dex2oat can accept now multiple profile files to drive a profile based
compilation. --profile-file and --reference-profile-file speficy a pair
of profile files which will be evaluated for significant differences
before starting the compilation. If the difference is insignificant
(according to some internal metric) the compilation is skipped and a
message is logged.

Multiple pairs of --profile-file and --reference-profile-file can be
specified. This effectively enables multi user support since profiles
for different users will be kept separately.

--reference-profile-file can be left out, case in which the decision is
solely based on --profile-file. If both flags are present, then their
repetition should form unique pairs.

If the compilation is performed and --reference-profile-file is given
then its data is merged with the data from the corresponding --profile-
file and saved back to the file.

If no profile flags are given, dex2oat proceeds as before and compiles
the dex files unconditionally.

As part of this change
- merge ProfileCompilationInfo and OfflineProfilingInfo under the same
object. There was no use to keep them separate anymore.
- SaveProfilingInfo now merges the data with what was in
the file before instead of overwriting it.

Bug: 26080105

Change-Id: Ia8c8b55587d468bca5179f78941854285426234d

1 files changed, 61 insertions, 0 deletions

diff --git a/compiler/profile_assistant.h b/compiler/profile_assistant.h
new file mode 100644
index 0000000000..088c8bd1c7
--- /dev/null
+++ b/compiler/profile_assistant.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_COMPILER_PROFILE_ASSISTANT_H_
+#define ART_COMPILER_PROFILE_ASSISTANT_H_
+
+#include <string>
+#include <vector>
+
+#include "jit/offline_profiling_info.cc"
+
+namespace art {
+
+class ProfileAssistant {
+ public:
+  // Process the profile information present in the given files. Returns true
+  // if the analysis ended up successfully (i.e. no errors during reading,
+  // merging or writing of profile files).
+  //
+  // If the returned value is true and there is a significant difference between
+  // profile_files and reference_profile_files:
+  //   - profile_compilation_info is set to a not null object that
+  //     can be used to drive compilation. It will be the merge of all the data
+  //     found in profile_files and reference_profile_files.
+  //   - the data from profile_files[i] is merged into
+  //     reference_profile_files[i] and the corresponding backing file is
+  //     updated.
+  //
+  // If the returned value is false or the difference is insignificant,
+  // profile_compilation_info will be set to null.
+  //
+  // Additional notes:
+  //   - as mentioned above, this function may update the content of the files
+  //     passed with the reference_profile_files.
+  //   - if reference_profile_files is not empty it must be the same size as
+  //     profile_files.
+  static bool ProcessProfiles(
+      const std::vector<std::string>& profile_files,
+      const std::vector<std::string>& reference_profile_files,
+      /*out*/ ProfileCompilationInfo** profile_compilation_info);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ProfileAssistant);
+};
+
+}  // namespace art
+
+#endif  // ART_COMPILER_PROFILE_ASSISTANT_H_